Revista de Biología Tropical ISSN: 0034-7744 ISSN: 2215-2075 Universidad de Costa Rica González-Sansón, Gaspar; Aguilar-Betancourt, Consuelo M.; Kosonoy-Aceves, Daniel Influence of sediment granulometry and salinity on the composition of an estuarine fish assemblage in the Mexican Tropical Pacific Revista de Biología Tropical, vol. 66, no. 3, July-September, 2018, pp. 1065-1077 Universidad de Costa Rica DOI: 10.15517/rbt.v66i3.31846 Available in: http://www.redalyc.org/articulo.oa?id=44959350010 How to cite Complete issue Scientific Information System Redalyc More information about this article Network of Scientific Journals from Latin America and the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Project academic non-profit, developed under the open access initiative Influence of sediment granulometry and salinity on the composition of an estuarine fish assemblage in the Mexican Tropical Pacific Gaspar González-Sansón1,2, Consuelo M. Aguilar-Betancourt1,2,* & Daniel Kosonoy-Aceves1 1. Departamento de Estudios para el Desarrollo Sustentable de la Zona Costera, Universidad de Guadalajara, Gómez Farías 82, San Patricio-Melaque, Cihuatlán, Jalisco, CP 48980, México. [email protected], [email protected], [email protected] 2. Canadian Rivers Institute, 100 Tucker Park Rd, Saint John, NB E2L 4A6, Canada. * Correspondence Received 15-II-2018. Corrected 29-V-2018. Accepted 27-VI-2018. Abstract: Barra de Navidad lagoon (BNL) is one of the main coastal wetlands in the coast of the State of Jalisco, Mexico. It is a Ramsar site (wetland of international importance) and has been included among the 81 mangrove sites with biological relevance and ecological rehabilitation needs in Mexico. Although fish fauna composition is well known in BNL, little evidence exists that support seasonal and spatial changes of fish assemblages’ struc- ture. The hypothesis tested in this study was that there are significant seasonal and spatial changes in BNL fish assemblages’ composition which can be explained, at least partially, by changes in salinity, water temperature and sediment’s granulometry. Fish assemblages were sampled monthly from October 2012 to September 2013 at four zones of BNL, using gill nets (7.62 mm stretched mesh). A sample was taken every month in a randomly selected area of each zone. Prior to each sampling operation, water salinity and temperature were measured using an YSI-30 probe. Samples of sediment were collected with a Van Veen grab sampler in three randomly selected points of each zone for granulometry and organic matter analyses. A total of 2 026 individuals belonging to 48 species were collected. Slightly more than 90 % of all caught fish belonged to nine species: Peruvian mojarra (Diapterus brevirostris), Pacific crevalle-jack (Caranx caninus), White mullet (Mugil curema), Blue sea-catfish (Ariopsis guatemalensis), Oval flounder (Syacium ovale), Pacific lined sole (Achirus mazatlanus), Yellowfin mojarra (Gerres simillimus), Pacific bumper (Chloroscombrus orqueta) and Freckled porcupinefish (Diodon holocanthus). Generalized linear models yielded significant differences among zones for the mean abundance of each of these nine species, but only in two cases seasonal differences were significant (D. brevisrostris and C. caninus). Permutational multivariate analysis of variance yielded also significant differences among zones and between seasons for the composition of the fish assemblage. Redundancy analysis using salinity, temperature, and percentage mud in sediment as environmental variables showed that fish assemblage’s composition varies along two main gradients defined by mud fraction of sediments in a small spatial scale (~ 3 km) and salinity in a seasonal scale. Percentage of variation explained by canonical axes was less than 25 %, indicating that other factors could be influencing changes in assemblage composition. As most species appear as juveniles in the lagoon, fluctuations in their abundances could be linked, at least partially, with recruitment events. Rev. Biol. Trop. 66(3): 1065-1077. Epub 2018 September 01. Key words: Fish assemblages; spatial changes, seasonal changes, coastal wetlands, Mexico, Eastern Tropical Pacific. Estuarine systems are important habitats habitats (Dahlgren et al., 2006) depend on the for adults and juveniles of numerous fish contribution these areas make to adult popula- species (Nagelkerken, 2009; Cowan, Yañez- tions in the adjacent shelf waters. A first step Arancibia, Sánchez-Gil, & Deegan, 2013). in the knowledge of this important aspect is The definition of such systems as nursery the documentation of the composition of fish areas (Beck et al., 2001) or essential juvenile assemblages considering not only the relative Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 66(3): 1065-1077, September 2018 1065 contribution of different species but also their and ecological rehabilitation needs by Mexi- length composition as a means to know the co’s National Commission for the Knowledge proportion of juvenile in each species. The and Use of Biodiversity (Rodríguez-Zúñiga studies of temporal and spatial variations of et al., 2013). Fish fauna in this lagoon is com- fish assemblage’s characteristics are essential posed in a great proportion (> 70 %) by species for the understanding of the factors driving in juvenile stages (González-Sansón et al., such variations. 2014) and it is highly probable that this wetland Temporal and spatial variability in the could be an important nursery area for many composition of estuarine fish assemblages has marine species with commercial and ecological been documented by several authors (Barletta, relevance (González-Sansón et al., 2016). Barletta-Bergan, Saint-Paul, & Hubold, 2003; Although fish fauna composition is well Rueda & Defeo, 2003; Ramos-Miranda et al., known in BNL, little evidence exists that 2005). Salinity gradients have been mentioned support seasonal and spatial changes of fish as a main factor structuring fish assemblages in assemblages’ structure. Therefore a study estuarine habitats (Araujo et al., 2002; Barletta, was designed to address spatial and temporal Barletta-Bergan, Saint-Paul, & Hubold, 2005) variations in fish fauna composition in the as well as the characteristics of the bottom lagoon. The hypothesis tested in this study including sediment’s granulometry and organic was that there are significant seasonal and matter contents (Vinagre, França, & Cabral, spatial changes in fish assemblages’ composi- 2006; Reis-Filho & Santos, 2014). tion which can be explained, at least partially, A review of pertinent literature on estua- by changes in salinity, water temperature and rine fish assemblages of Mexican Pacific coast sediment’s granulometry. yielded only qualitative mentions on the pres- ence of juvenile fish in coastal lagoons and MATERIAL AND METHODS other estuarine systems. In most cases, the authors did not measure the collected fish Barra de Navidad lagoon is located in and mention of the presence of juveniles is the southern coast of Jalisco State, Mexico therefore not supported with quantitative data (19°11’25’’ N & 104°39’53’’ W). It has a water (Díaz, Cano-Quiroga, Aguirre-León, & Ortega- surface of 334 ha and is surrounded by a well Bernal, 2004; Benítez et al., 2007; Rodríguez- developed mangrove forest (571 ha) mainly Romero et al., 2011). Two papers were found in its northeastern and southeastern margins which report limited information about fish (Fig. 1). Fresh water inputs in the western lengths of some species in coastal lagoons extreme of the lagoon come from the Arroyo (Amezcua-Linares, 1977; Mendoza, Castillo- Seco River and an artificial channel commu- Rivera, Zárate-Hernández, & Ortiz-Burgos, nicating the lagoon with the Marabasco River. 2009) but the majority of studies were not Some fresh water input is also present in the focused in documenting size composition of north-western side of the lagoon coming from fishes. Only recent research in Barra de Navi- urban drainage of Barra de Navidad town. dad lagoon has yielded the first quantitative The lagoon communicates permanently with data on fish lengths suggesting a dominance sea through a 100 m wide mouth. Based on of juvenile fish in these systems (González- a 64 years record (1946 to 2010) two seasons Sansón et al., 2014, 2016). related to rainfall are defined for the lagoon Barra de Navidad lagoon (BNL) is one of (Gonzalez-Sanson et al., 2014): A rain season the main coastal wetlands in the coast of the from June to October and a dry season from State of Jalisco, Mexico. This lagoon has been November to May. declared Ramsar site (wetland of international The research was performed on fish sam- importance) and has been included among the pled monthly from October 2012 to September 81 mangrove sites with biological relevance 2013 at four zones of Barra de Navidad lagoon 1066 Rev. Biol. Trop. (Int. J. Trop. Biol. ISSN-0034-7744) Vol. 66(3): 1065-1077, September 2018 Fig. 1. Sampling zones in Barra de Navidad lagoon. (Fig. 1). The zones were defined based on collected with a Van Veen grab sampler in three natural basins of the lagoon (the bigger, most randomly selected points of each zone. A sub- eastern basin was divided in two zones). One sample of 200-250 g of sediment was used for sample was taken at each zone each month. the estimation of grain size composition based The position of sampling in each zone was on methodology by Folk (1974) and three frac- selected randomly for each sampling opera- tions were defined based in particle size as mud tion. Sampling gear was a gill net of 180 m (≤ 0.0625 mm), sand (> 0.0625 and ≤ 2.00 mm length, 2.7 m high and 7.62 cm mesh size. The ) and gravel (> 2.00 mm). Organic matter con- net was deployed forming a circle and then tent was estimated from weight loss of a sub- was collected maintaining the circle closed sample burned at 550 °C during one hour and and progressively reducing its diameter. This expressed as percentage of dry weight. maneuver forced fish inside de encircled area Variations of the number of individu- to try to escape and get meshed.